(1) Field of the Invention
This invention relates to an antilock brake system, and more specifically a solenoid-supporting device for an antilock brake system by which the vibration and noise, which are created from solenoid valves when a vehicle runs, are attenuated and the heat generated from the solenoid valves are effectively radiated, thereby preventing the damage of the solenoid valves' coils.
(2) Description of the Prior Art
In general, an antilock brake system is an apparatus for securing the steering stability and driving power through the prevention of the slippage of a running vehicle. It provides the stable brake effect by properly controlling the braking pressure exerting to each wheel when braking a vehicle.
FIG. 1 is a schematic hydraulic circuit diagram of a general antilock brake system. As shown in the figure, brakes 6 generating a braking power by means of a hydraulic pressure are mounted on the respective wheels 5, and a brake pedal 1 is provided at the driver's seat. The brake pedal 1 is connected with a pressure booster 2 for boosting the braking pressure, an oil storage tank 4 for storing the brake oil, and a master cylinder 3 for compressing the oil in the oil storage tank 4 at a high pressure through the boosting pressure of the pressure booster 2 and transmitting it to the brake 6.
At the inlet and outlet of each brake 6 are mounted a normal open type solenoid valve 7 and a normal close type solenoid valve 8 for controlling the flow of the hydraulic oil, respectively. The operation of the solenoid valves 7 and 8 is controlled by an ECU 20 which detects a vehicle's speed through a wheel sensor 9 mounted on the wheel 5.
At the downstream of the normal close type solenoid valve 8 are mounted a low pressure accumulator 11 and a high pressure accumulator 12 for temporarily storing the oil discharged from the brake 6. Between the low pressure accumulator 11 and the high pressure accumulator 12 is mounted a pump 13 that pumps the oil in the low pressure accumulator 11 to the high pressure accumulator 12.
The low and high pressure accumulators 11 and 12, the pump 13, and the normal open and close type solenoid valves 7 and 8 are housed in the inside of a modulator 30, and the ECU 20 is mounted on the underside of the modulator 30. Such a structure of the modulator 30 will be described with reference to FIGS. 7 and 8. Hereinafter, the normal open type solenoid valve 7 and the normal close type solenoid valve 8 will be indicated as only a solenoid valve 7.
The modulator 30 includes a block 31 of an aluminum alloy material in which the solenoid valves 7 are mounted. The ECU 20 includes a housing 21 having four side walls and a printed circuit board 23 which is mounted at a space 22 formed at a lower portion of the housing 21. The four corners of the housing 21 are fastened to those of the modulator block 31 by bolts 24.
The solenoid valve 7 comprises a solenoid 7a which creates an electric field by an applied electric power and a valve body 7b which opens or closes an oil passage formed therein by interacting with the electric field created by the solenoid 7a. The solenoid 7a is mounted on the housing 21 of the ECU 20 and the valve body 7b is mounted on the block 31 of the modulator 30. The solenoid 7a includes wounded coils 17 and a yoke 18 enclosing the coils 17, and wires 19 which extend outside to be connected to the printed circuit board 23.
Between the modulator block 31 and the ECU housing 21 is provided a supporting device 40 for urging the solenoids 7a to the ECU housing 21 to prevent the vibration and noise caused by the movement of the solenoids 7a in the ECU housing 21. The supporting device 40 comprises a base plate 41 which contacts the bottom surface of the modulator block 31 and a plurality of elastic members 42 which are branched off from the base plate 41 and bent downward at a given angle so as to contact the top surface of each solenoid 7a.
Thus, when the modulator block 31 is combined with the ECU housing 21, the valve bodies 7b pass through the spaces formed between the respective elastic members 42 and are fitted to the corresponding solenoids 7a, and the front ends of the elastic members 42, as shown in FIG. 8, support the solenoids 7a in a point contact with the top surfaces of the solenoids 7a.
However, such a solenoid-supporting device for an antilock brake system as aforementioned has a disadvantage in that it does not effectively radiate the heat generated from the solenoids during the operation of the solenoid valves because it supports the solenoids in a point contact with the solenoids. That is, when the solenoid valves operates, heat is generated from the solenoids. Thus, if the heat is not radiated effectively, it may cause the problems that the coils are burnt, and therefore the brake system does not operate.